OPTIMIZING SUSTAINABLE STONE FRUIT PRODUCTION PRACTICES IN FLORIDA

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 0224027
• Project Start Date: Oct 1, 2010
• Project End Date: Oct 1, 2015
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIVERSITY OF FLORIDA
G022 MCCARTY HALL
GAINESVILLE,FL 32611

Performing Department
Horticultural Science

Non Technical Summary
The Florida stone fruit industry once had a thriving industry of over 1600 hectares, however in 2009, current estimates placed stone fruit acreage at approximately 400 hectares statewide, with a growing portion of these plantings in Central and South Florida. Over the past 50 years, the University of Florida stone fruit breeding program has released stone fruit varieties well suited to low chill production areas with tens of thousands of hectares planted worldwide. During the last decade, low chill peach cultivars with non-melting flesh have allowed delayed harvest leading to greater physiological maturity and fruit quality. These characteristics allow growers to take advantage of a unique marketing window to maximize economic returns. Several key growers in Central and Southern Florida have planted more than 120 hectares. The objective of this grower effort is the development of a subtropical peach industry focused on producing early season fruit. The major markets for these fruit are medium to large sized supermarket chains and several smaller niches including farmers markets, fruit stands, and community supported agriculture (CSA) farms. Economic analyses of establishment, production, and identifying marketing opportunities are essential to continued growth of the subtropical stone fruit industry. Development of sustainable practices to support industry expansion is an important function of this project. Currently, the industry is limited to one commercially recommended rootstock, Flordaguard due to the presence of an endemic root-knot nematode, Meloidogyne floridensis, as other root-knot nematode resistant rootstocks are not resistant to this particular nematode. It is essential that other rootstocks be developed and evaluated as the industry expands to enhance biodiversity. Increased pressure on agricultural producers to adhere to new standards for nutrient levels in agricultural wastewater has brought fertilization and irrigation practices to the forefront. Much of the research on nutrition in stone fruit has been conducted in temperate climates where fruit development and shoot growth coincide. In subtropical climates, fruit production is rapid in the early growing season, and trees continue to produce vegetative biomass well into the autumn season. Much of the expanding stone fruit industry is being planted in areas with sandy soil types, which have a high leaching potential. Thus, application method, rates of plant nutrients, and costs must be examined for production in these subtropical climates to ensure environmental sustainability.

Animal Health Component

(N/A)

Research Effort Categories

Basic

(N/A)

Applied

(N/A)

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
212	1114	1020	33%
205	1114	1020	33%
102	1114	1010	34%

Knowledge Area
212 - Pathogens and Nematodes Affecting Plants; 102 - Soil, Plant, Water, Nutrient Relationships; 205 - Plant Management Systems;

Subject Of Investigation
1114 - Peach;

Field Of Science
1010 - Nutrition and metabolism; 1020 - Physiology;

Keywords

flordaguard rootstock

low-chill peach varieties

nitrogen rates

irrigation rates

root-knot nematode

meloidogyne floridensis

Goals / Objectives
The objective of this project is to develop sustainable production practices for subtropical stone fruit production. Specific objectives of this project include 1) evaluate scion and rootstock of new plant material for horticultural characteristics; 2) evaluate rootstock material for resistance to Meloidogyne floridensis and investigate mechanism of resistance and/or tolerance in Flordaguard rootstock; 3) optimize fertilization and irrigation practices for maximum output of high quality fruit in conjunction with economic analyses.

Project Methods
Objective 1: Scion and rootstock evaluations placed in three locations statewide. Trees will be irrigated with microsprinklers, with overhead irrigation for freeze protection. All production practices will be planted at a typical commercial density and managed according to recommended practices. Scion material will be evaluated for disease resistance, tree growth habit, and fruit quality attributes (soluble solids content, pH, titratable acidity, fruit size, fruit firmness, peel and flesh color) at commercial maturity in replicate. Information from these evaluations will be used to author appropriate patents and informational material for variety releases. These new varieties and rootstocks will then be incorporated into extension publications and statewide stone fruit programs. Objective 2: The experimental orchards will be established at two Florida locations. Rootstock performance will be measured in terms of tree survival, growth, yield, and fruit quality. Tree survival will be determined by calculation of the percentage of trees alive every 6 months, and amount of rootstock galling will be rated. Tree growth will be determined by plant height, trunk diameter, and canopy diameter. Fruit yield (kg per tree and fruit number with classification of marketable and non-marketable fruit), and postharvest fruit quality (fruit peel and flesh color, fruit size, soluble solids content, pH, titratable acidity; sampled at 3-day intervals) will be evaluated to determine the commercial potential of rootstock selections. Appropriate statistical methods will be used to analyze data. Objective 3: The experimental orchard for this study will be established and trained to a perpendicular-V system. The orchard will be irrigated and managed as noted above. Treatments will be set up in a randomized complete block design. Growth and fruit attributes measured for each replicate will be treated separately in statistical analysis. Treatments will include various N rates applied in fertigation system to investigate suboptimal, optimal, and excessive N rate amounts and their effects on growth. Phosphorus and potassium rates will be kept constant. To assess nitrogen leaching, a soil solution sampling device will be installed in replicate and collected at regular intervals. A 1-m herbicide strip will be maintained to minimize weed competition. Tree growth will be measured by: pruning weights (dormant and summer), shoot length (terminal and lateral) and trunk cross-sectional area. Leaf samples will be collected to assess nitrogen and chlorophyll content. Fruit quality will be analyzed as described above. Total nitrogen uptake will be assessed by destructively sampling a subset of trees. The results from this objective will be used to provide precise N management to growers and for distribution through statewide extension programs and personnel.

Progress 10/01/10 to 10/01/15

Outputs
Target Audience:The primary target audiences for this project are stone fruit producers in the southeastern United States, and research and extension scientists working in stone fruit production. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?In this project, we trained fourgraduate students, with two students finishing their degrees in May, 2016. Mary Ann Maquilan (Ph.D. Student), Zilfina Rubio-Ames (M.S. Student), Carlos Zambrano-Vaca (M.S. Student), Elizabeth Conlan (M.S. student) In addition, a biological scientist, Moshe Doron is gaining additional training to enhance his professional development in his position. How have the results been disseminated to communities of interest?This information has been distributed via websitessuch as the UF Stone Fruit Research and Extension website (http://hos.ufl.edu/stonefruit/) and the UF Stone Fruit Extension Blog (http://ufstonefruit.wordpress.com/), and various peer reviewed publications. A video about the main fertilization experiment is posted online and informs growers about the project and the early progress that has been made. Furthermore, traditional methods of dissemination have been utilized, such as newsletters, magazine articles, field days, and extension documents have implemented several aspects of this project. ? What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Rootstock Evaluation Four rootstocks with commercial potential (T. Beckman, USDA-ARS, Byron, GA) were established and budded with 'UFOne' in Citra, FL. Initial trunk cross sectional area (TCSA) taken in October 2014 indicated that clonally propagated 'Flordaguard' was significantly larger than P-47 and MP-29 rootstock, while the number of suckers produced did not differ. Rootstocks did not have an effect on summer pruning weights (June, 2015), although both P-47 and MP-29 tended to have lower pruning weights than 'Flordaguard', a standard rootstock in the industry. Further data collection is needed on fruit production, specifically yield, fruit size, fruit quality, and fruit number per tree to optimize rootstock selection for new peach orchards in Florida. This planting is replicated in Punta Gorda, FL at a commercial grower site to evaluate rootstocks for spring shock syndrome. Nematode Resistance in Subtropical Peach Rootstocks Preliminary field evaluation of Flordaguard x Prunus kansuensis and Okinawa x P. kansuensis F1 hybrids indicates that the former hybrids are resistant to M. floridensis, while the Okinawa x P. kansuensis hybrids is susceptible. These preliminary results indicate that P. kansuensis may carry a resistance gene(s) allelic to that found in Flordaguard. Initial backcrosses were made to test the hypothesis and seed set, harvested, and stratified for germination. All seedlings have been phenotyped and are undergoing genotyping to confirm resistance genes. There was a significant delay in this project; it was found that the existing population of M. floridensis was no longer infectious to peach roots, and a secondary population of M. floridensis had to be isolated had to be bulked so that seedlings could be inoculated. A separate multi-state study to investigate reduced rates of Telone (1,3-Dichloropropene) found that rates at half the recommended rates were as effective as the full rates; however the initial M. floridensis inoculations were found to not be virulent on peach roots after two years. Thus, we concentrated on nematode survey work in a control (no Telone), full and half rate treatments of Telone II. Soil sampling for juvenile nematodes were conducted in August (2013), December and February (2014), and July 2014. Large amounts of root-knot nematodes were found in control plots (without fumigation) and are suspected to be M. floridensis, however other species not known to infect peach roots were found and will be used to secure funding for future peach rootstock/nematode interaction research. Optimal Nitrogen Rates Four nitrogen treatments and a control (no nitrogen added) were applied to mature TropicBeauty trees beginning in spring of 2011, throughout 2012 and 2013. These treatments include: N0 = 0 kg/ha (0 lb N/acre) N1 = 45 kg N/ha (40 lb N/acre) N2 = 90 kg N/ha (80 lb N/acre) N3 = 179 kg N/ha (160 lb N/acre) N4 = 269 kg N/ha (240 lb N/acre) Trunk caliper measurements, vegetative and floral bud measurements were recorded, and soil samples at two depths were taken throughout the plot. Single tree replicates were set up in a completely randomized design (N=6). A severe freeze in February 2012 reduced crop on all trees throughout the orchard to 20% of a full crop. Remaining fruit were harvested and analyzed for fruit color, Brix, pH, and titratable acidity (TA). Fruit size and total yield was recorded for each replicate. In 2012, there were no differences in fruit quality as determined by brix, pH, or TA; however trees with 179 and 269 kg/ha had higher pruning weights, leaf nitrogen levels and chlorophyll content compared to the lower nitrogen rates and the control. In 2013, a near normal fruit crop was harvested and fruit quality measurements were again recorded. Summer pruning weights and total leaf nitrogen was measured and analyzed for each treatment in 2011-2013.Three years of work (2011-2014) indicated that leaf nitrogen % were excessive in all treatments, including those which received no nitrogen. In 2014, trees with the highest rate of nitrogen (N4) significantly produced higher pruning weights than those receiving no nitrogen. Fruit size was highest in the highest rate (N4) in 2013, while it was largest in the moderate rate (N3) in 2014. Considering there was no difference for a third year in fruit yield, brix, pH, or TA, a general recommendation is being made to reduce the amount of nitrogen fertilizer applied to approximately 80-90 lbs. N/acre annually, depending upon individual site and soil characteristics. In a young orchard, an additional subplot factor was added: application method (granular [banded] vs. fertigation). The same nitrogen treatments were applied throughout the growing season either monthly (granular applications) or daily (fertigation applications). Leaching potential is being analyzed by soil sampling at key phenological stages throughout the growing season. Although nitrate levels and EC readings are higher at 1.2 and 1.5 m depths from both the 179 and 269 kg/ha treatments, they are well below the maximum amounts determined by the US Environmental Protection Agency.Overall, soil EC content and soil nitrate levels were lower in trees that were fertigated vs. granular treatments. Fruit size and yield was largest in trees receiving 90 - 179 kg/ha, however tree size was smaller in the 90 kg/ha, reducing overall labor costs for pruning and thinning. Research program findings were disseminated to scientists through participation in scientific meetings and scientific publications.

Publications

• Type: Journal Articles Status: Accepted Year Published: 2015 Citation: Z. Rubio Ames, M. Olmstead, R. Darnell, and C. Sims. 2015. Effect of shoot and cluster thinning on vine performance, fruit and wine quality of Blanc Du Bois. Journal of the American Pomological Society.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: M.A. Olmstead, J. Gilbert, T. Colquhoun, D. Clark, R. Kluson, and H. Moskowitz. 2015. In Pursuit of the Perfect Peach: Consumer-Assisted Selection of Peach Fruit Traits. HortScience. 50:1202-1212.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Olmstead, M., L. Zotarelli, J. Brecht, and M. Ross. 2015. Impact of Nitrogen on Vegetative Growth of Mature Peach Trees in a Subtropical Climate. Acta Horticulturae. 1084:459-464.
• Type: Other Status: Published Year Published: 2015 Citation: J.G. Williamson, M. Olmstead, J.H. Crane, T. Vashisth, and R.E. Rouse. 2015. Dooryard Fruit Varieties. FC23/MG248. Accepted 18 June 2015. http://edis.ifas.ufl.edu/mg248
• Type: Other Status: Published Year Published: 2015 Citation: S. Sherman, M. Olmstead, P. Harmon, and T. Beckman. 2015. Peach Fungal Gummosis. Accepted 8 July 2015. http://edis.ifas.ufl.edu/pdffiles/HS/HS126500.pdf
• Type: Other Status: Published Year Published: 2015 Citation: C. Ligon, M. Olmstead, and P. Harmon. 2015. Peach Rust. Accepted 29 June 2015. http://edis.ifas.ufl.edu/pdffiles/HS/HS126300.pdf
• Type: Journal Articles Status: Under Review Year Published: 2015 Citation: Edenbrandt, A., L. House, Z. Gao, M. Olmstead, D. Gray. 2015. Consumer acceptance of cisgenic food and the impact of information and reference points. Journal of Agricultural Economics. In review.
• Type: Journal Articles Status: Accepted Year Published: 2015 Citation: C. Zambrano-Vaca, M. Olmstead, L. Zotarelli, N. Boyd and B. Santos. 2015. Plastic Roof Materials as They Affect Bell Pepper Production in High Tunnels. International Journal of Vegetable Science. Accepted
• Type: Websites Status: Published Year Published: 2015 Citation: https://ufstonefruit.wordpress.com/

Progress 10/01/14 to 09/30/15

Outputs
Target Audience:The primary target audiences for this project are stone fruit producers in the southeastern United States, and research and extension scientists working in stone fruit production. ? Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?In this project, we trained fourgraduate students, with two students finishing their degrees in May, 2016. Mary Ann Maquilan (Ph.D. Student), Zilfina Rubio-Ames (M.S. Student), Carlos Zambrano-Vaca (M.S. Student), Elizabeth Conlan (M.S. student) In addition, a biological scientist, Moshe Doron is gaining additional training to enhance his professional development in his position. How have the results been disseminated to communities of interest?The results have been reported in peer-reviewed journal articles, newsletters, magazine outlets targeting growers, and via field day presentations. In addition, important findings and cautions are reported via a website blog and a listserv containing many of the growers in the State of Florida. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Rootstock Evaluation In 2014, initial trunk cross sectional area (TCSA) indicated that clonally propagated 'Flordaguard' was significantly larger than P-47 and MP-29 rootstock, while the number of suckers produced did not differ. Rootstocks did not have an effect on summer pruning weights (June, 2015), although both P-47 and MP-29 tended to have lower pruning weights than 'Flordaguard', a standard rootstock in the industry. This planting is replicated in Punta Gorda, FL at a commercial grower site to evaluate rootstocks for spring shock syndrome. Nematode Resistance in Subtropical Peach Rootstocks Preliminary field evaluation of Flordaguard x Prunus kansuensis and Okinawa x P. kansuensis F1 hybrids indicates that the former hybrids are resistant to M. floridensis, while the Okinawa x P. kansuensis hybrids is susceptible. These preliminary results indicate that P. kansuensis may carry a resistance gene(s) allelic to that found in Flordaguard. Initial backcrosses were made to test the hypothesis and seed set, harvested, and stratified for germination. All seedlings have been phenotyped and are undergoing genotyping to confirm resistance genes. There was a significant delay in this project; it was found that the existing population of M. floridensis was no longer infectious to peach roots, and a secondary population of M. floridensis had to be isolated had to be bulked so that seedlings could be inoculated. Two different populations of Mf -one, a resident population on peach and the other, a resident population on a vegetable, are being maintained in the greenhouse on a tomato host. We are also developing criteria for evaluating nematode resistance in current rootstocks used in the Florida peach industry, as well as potential hybrid rootstocks. Peach seedling rootstocks are being maintained as to provide optimal conditions for root growth. Sufficient populations of nematodes were reared and used to inoculate these seedlings (10,000 eggs/plant). After two months, plants were phenotyped and ongoing genotyping will give information on tolerance/resistance of these existing and potential peach rootstocks. Optimal Nitrogen Rates In 2014-15, this experiment continued with the following nitrogen treatments: N0 = 0 kg/ha (0 lb N/acre) N1 = 45 kg N/ha (40 lb N/acre) N2 = 90 kg N/ha (80 lb N/acre) N3 = 179 kg N/ha (160 lb N/acre) N4 = 269 kg N/ha (240 lb N/acre) All plots were converted to fertigation. Single tree replicates were set up in a completely randomized design (N=6). Trunk caliper measurements, distribution of vegetative and floral bud measurements were recorded, and soil samples at two depths were taken throughout the plot (5 times/yr). In both years, fruit were harvested and analyzed for fruit color, firmness, Brix, pH, and titratable acidity (TA). Fruit size and total yield was recorded for each replicate. In 2014, there were no differences in fruit quality as determined by brix, pH, or TA; however trees with 179 and 269 kg/ha had higher pruning weights, leaf nitrogen levels and chlorophyll content compared to the lower nitrogen rates and the control. Leaching potential is being analyzed by soil sampling at key phenological stages throughout the growing season. Although nitrate levels and EC readings are higher at 1.2 and 1.5 m depths from both the 179 and 269 kg/ha treatments, they are well below the maximum amounts determined by the US Environmental Protection Agency.Overall, soil EC content and soil nitrate levels were lower in trees that were fertigated vs. granular treatments. Fruit size and yield was largest in trees receiving 90 - 179 kg/ha, however tree size was smaller in the 90 kg/ha, reducing overall labor costs for pruning and thinning. Three years of previous work with this project (2011-2014) indicated that leaf nitrogen % were excessive in all treatments, including those which received no nitrogen. In 2014, trees with the highest rate of nitrogen (N4) significantly produced higher pruning weights than those receiving no nitrogen. Fruit size was highest in the highest rate (N4) in 2013, while it was largest in the moderate rate (N3) in 2014. Considering there was no difference for a third year in fruit yield, brix, pH, or TA, a general recommendation is being made to reduce the amount of nitrogen fertilizer applied to approximately 80-90 lbs. N/acre annually, depending upon individual site and soil characteristics. Research program findings were disseminated to scientists through participation in scientific meetings and scientific publications.

Publications

• Type: Journal Articles Status: Accepted Year Published: 2016 Citation: Z. Rubio Ames, M. Olmstead, R. Darnell, and C. Sims. 2015. Effect of shoot and cluster thinning on vine performance, fruit and wine quality of Blanc Du Bois. Journal of the American Pomological Society. Accepted.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: M.A. Olmstead, J. Gilbert, T. Colquhoun, D. Clark, R. Kluson, and H. Moskowitz. 2015. In Pursuit of the Perfect Peach: Consumer-Assisted Selection of Peach Fruit Traits. HortScience. 50:1202-1212.
• Type: Journal Articles Status: Awaiting Publication Year Published: 2015 Citation: C. Zambrano-Vaca, M. Olmstead, L. Zotarelli, N. Boyd and B. Santos. 2015. Plastic Roof Materials as They Affect Bell Pepper Production in High Tunnels. International Journal of Vegetable Science. Accepted
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Olmstead, M., L. Zotarelli, J. Brecht, and M. Ross. 2015. Impact of Nitrogen on Vegetative Growth of Mature Peach Trees in a Subtropical Climate. Acta Horticulturae. 1084:459-464.
• Type: Other Status: Published Year Published: 2015 Citation: J.G. Williamson, M. Olmstead, J.H. Crane, T. Vashisth, and R.E. Rouse. 2015. Dooryard Fruit Varieties. FC23/MG248. Accepted 18 June 2015. http://edis.ifas.ufl.edu/mg248
• Type: Other Status: Published Year Published: 2015 Citation: S. Sherman, M. Olmstead, P. Harmon, and T. Beckman. 2015. Peach Fungal Gummosis. Accepted 8 July 2015. http://edis.ifas.ufl.edu/pdffiles/HS/HS126500.pdf
• Type: Other Status: Published Year Published: 2015 Citation: C. Ligon&, M. Olmstead, and P. Harmon. 2015. Peach Rust. Accepted 29 June 2015. http://edis.ifas.ufl.edu/pdffiles/HS/HS126300.pdf

Progress 10/01/13 to 09/30/14

Outputs
Target Audience: The primary target audiences for this project are stone fruit producers in the southeastern United States, and research and extension scientists working in stone fruit production. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? In this project, we are training fourgraduate students, with two graduate students finishing in December 2014. Mary Ann Maquilan (Ph.D. Student), Zilfina Rubio-Ames (M.S. Student), Carlos Zambrano-Vaca (M.S. Student), Elizabeth Conlan (M.S. student) In addition, a biological scientist, Matthew Ross is gaining additional training to enhance his professional development in his position. How have the results been disseminated to communities of interest? This information has been distributed via websitessuch as the UF Stone Fruit Research and Extension website (http://hos.ufl.edu/stonefruit/) and the UF Stone Fruit Extension Blog (http://ufstonefruit.wordpress.com/). A video about the main fertilization experiment is posted online and informs growers about the project and the early progress that has been made. Furthermore, traditional methods of dissemination have been utilized, such as newsletters, magazine articles, field days, and extension documents have implemented several aspects of this project. What do you plan to do during the next reporting period to accomplish the goals? During the next reporting period, publications based on both the nitrogen and rootknot nematode research projects will be submitted and projects will be completed. However, this research has led to new questions, both of which have been funded into 2017. A nematode screening assay will be developed as to ease identificationand severity ofgalling in peach rootstocks. We plan to genotype all F2 populations in our backcross population of rootstock seedlings to begin mapping of potential resistance/tolerance genes for M. floridensis resistance. The rootstock evaluation data collection will continue in both Citra, FL and Punta Gorda, FL and include: trunk-cross-sectional area, suckering, and pruning weights. Finally, we will continue our measurements on horticultural characteristics of potential rootstocks for peaches in subtropical environments.

Impacts
What was accomplished under these goals? Rootstock Evaluation Four rootstocks with commercial potential (T. Beckman, USDA-ARS, Byron, GA) were established and budded with ‘UFOne’ in Citra, FL. Initial trunk cross sectional area (TCSA) were collected at planting and will be collected in January 2015. Bloom date, number of suckers and pruning weights will be collected to evaluate rootstocks with commercial potential. Nematode Resistance in Subtropical Peach Rootstocks Preliminary field evaluation of Flordaguard x Prunus kansuensis and Okinawa x P. kansuensis F1 hybrids indicates that the former hybrids are resistant to M. floridensis, while the Okinawa x P. kansuensis hybrids is susceptible. These preliminary results indicate that P. kansuensis may carry a resistance gene(s) allelic to that found in Flordaguard. Initial backcrosses were made to test the hypothesis and seed set, harvested, and stratified for germination. Foundation populations of M. floridensis are established and in continual regeneration for the genetic study of resistance/tolerance in Flordaguard. A separate multi-state study to investigate reduced rates of Telone (1,3-Dichloropropene) is in its second year, however tree growth has been very poor due to heavy rains throughout late June and July. Soil sampling for juvenile nematodes are being conducted in August (2013), December and February (2014). Large amounts of root-knot nematodes were found in control plots (without fumigation) and are suspected to be M. floridensis. Optimal Nitrogen Rates Four nitrogen treatments and a control (no nitrogen added) were applied to mature TropicBeauty trees beginning in spring of 2011, throughout 2012 and 2013. These treatments include: N0 = 0 kg/ha (0 lb N/acre) N1 = 45 kg N/ha (40 lb N/acre) N2 = 90 kg N/ha (80 lb N/acre) N3 = 179 kg N/ha (160 lb N/acre) N4 = 269 kg N/ha (240 lb N/acre) Trunk caliper measurements, vegetative and floral bud measurements were recorded, and soil samples at two depths were taken throughout the plot. Single tree replicates were set up in a completely randomized design (N=6). A severe freeze in February 2012 reduced crop on all trees throughout the orchard to 20% of a full crop. Remaining fruit were harvested and analyzed for fruit color, Brix, pH, and titratable acidity (TA). Fruit size and total yield was recorded for each replicate. In 2012, there were no differences in fruit quality as determined by brix, pH, or TA; however trees with 179 and 269 kg/ha had higher pruning weights, leaf nitrogen levels and chlorophyll content compared to the lower nitrogen rates and the control. In 2013, a near normal fruit crop was harvested and fruit quality measurements were again recorded. Summer pruning weights and total leaf nitrogen was measured and analyzed for each treatment in 2011-2013. In a young orchard, an additional subplot factor was added: application method (granular [banded] vs. fertigation). The same nitrogen treatments were applied throughout the growing season either monthly (granular applications) or daily (fertigation applications). Leaching potential is being analyzed by soil sampling at key phenological stages throughout the growing season. Although nitrate levels are higher at 1.2 and 1.5 m depths from both the 179 and 269 kg/ha treatments, they are well below the maximum amounts determined by the US Environmental Protection Agency. Research program findings were disseminated to scientists through participation in scientific meetings and scientific publications.

Publications

• Type: Journal Articles Status: Published Year Published: 2013 Citation: Morgan, K. and M. Olmstead. 2013. A Diversification Strategy for Perennial Horticulture in Florida. HortTechology. 23(4):482-489.
• Type: Journal Articles Status: Published Year Published: 2012 Citation: Olmstead, M.A., T.W. Miller, C.S. Bolton (g), and C.A. Miles. 2012. Weed Control in a Newly Established Organic Vineyard. HortTechnology. 22:757-765.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2013 Citation: Morgan, K. and M. Olmstead. 2013. Peach orchard establishment and production planning budgets for Florida. Proceedings of the Florida State Horticultural Society.
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Olmstead, M. 2013. Low-chill peach production in Florida. 2012 Proceedings of the Florida State Horticultural Society.
• Type: Other Status: Published Year Published: 2013 Citation: Olmstead, M.A., J. Chaparro, J.G. Williamson, R. Rouse, R. Mizell, P. Harmon, and J. Ferguson. 2013. Florida Subtropical Peaches and Nectarines: Production Practices. .
• Type: Other Status: Published Year Published: 2013 Citation: Olmstead, M.A., and K. Morgan. 2013. Orchard Establishment and Production Budget for Stone Fruit Production in Florida. .
• Type: Other Status: Published Year Published: 2013 Citation: Olmstead, M.A., J. Chaparro, P. Andersen, J. Williamson, and J. Ferguson. 2013. Florida Peach and Nectarine Varieties. .
• Type: Journal Articles Status: Accepted Year Published: 2014 Citation: M. Keller, L.J. Mills, and M.A. Olmstead. 2014. Fruit ripening has little influence on grapevine cold acclimation. American Journal of Enology and Viticulture.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Olmstead, M. and D. James. 2014. Ecosystem Approaches to Managing Insect and Mite Populations Effectively in Inland Desert Vineyards Utilizing Sustainable Production Practices  A Review. Journal of the American Pomological Society. 68(2):97-110.
• Type: Other Status: Awaiting Publication Year Published: 2014 Citation: D. Mancero-Castillo, M. Olmstead, P. Harmon. 2014. Peach Scab. University of Florida Extension Service. Online.

Progress 10/01/12 to 09/30/13

Outputs
Target Audience: The primary target audiences for this project are stone fruit producers in the southeastern United States, and research and extension scientists working in stone fruit production. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? In this project, we have trained one Doctor of Plant Medicine candidate, and three other graduate students. Mary Ann Maquilan (Ph.D. Student), Zilfina Rubio-Ames (M.S. Student), Carlos Zambrano-Vaca (M.S. Student), Daniel Mancero-Castillo (Doctor of Plant Medicine Candidate) In addition, a biological scientist, Matthew Ross is gaining additional training to enhance his professional development in his position. How have the results been disseminated to communities of interest? Research program findings were disseminated to scientists through participation in scientific meetings and scientific publications. Outreach information has been distributed via websitessuch as the UF Stone Fruit Research and Extension website (http://hos.ufl.edu/stonefruit/) and the UF Stone Fruit Extension Blog (http://ufstonefruit.wordpress.com/). A video about the main fertilization experiment is posted online and informs growers about the project and the early progress that has been made. Furthermore, traditional methods of dissemination have been utilized, such as newsletters, magazine articles, field days, and extension documents have included various results of this project. What do you plan to do during the next reporting period to accomplish the goals? During the next reporting period, research projects on rootstock evaluation will be re-established, with initial data being collected on trunk-cross-sectional area, suckering, and pruning weights. Although funding for aspect ofexamining nematode resistance in peach rootstocks has ended, a separate study was funded, and this research will continue. A nematode screening assay will be developed as to ease identificationand severity of galling in peach rootstocks. We plan to genotype all F2 populations in our backcross population of rootstock seedlings to begin mapping of potential resistance/tolerance genes for M. floridensis resistance. Finally, we will continue our measurements on horticultural characteristics of potential rootstocks for peaches in subtropical environments. Optimization of nitrogen rates will continue, with a final year of data collection, since frost events severely reduced cropload in our newly established orchard.All measurements will be repeated to assess year-to-year variability and the effects of the treatments on the tree growth and fruit quality. Funding is being sought for timing of fertilization to optimize fruit and tree growth.

Impacts
What was accomplished under these goals? The unique growing conditions in Florida allow producers to sell peaches when there is little else on the market, after imports from South America have slowed. This allows growers to command a premium price with increasing demand from consumers for this tree-ripe Florida fruit. However, these unique growing conditions in a subtropical environment demand that production practices are altered to produce premium quality fruit. Identifying the ideal nitrogen rate will allow growers to produce high quality fruit while minimizing environmental impacts from leaching and optimize tree health and longevity. Optimizing tree health is maximized in Florida by growing scions on rootstocks that are resistant to Meloidogyne floridensis, the peach root-knot nematode currently only found within the state of Florida. A sole commercially-acceptable resistant rootstock, Flordaguard is particularly susceptible to fungal gummosis. Thus, identifying genes associated with peach root-knot nematode resistance in Flordaguard will allow us to construct markers associated with this trait. These marker(s) can then be used in marker-assisted breeding efforts, which will greatly decrease the time to breed additional rootstocks containing resistance to M. floridensis.

Publications

• Type: Other Status: Published Year Published: 2013 Citation: Olmstead, M.A., J. Chaparro, P. Andersen, J. Williamson, and J. Ferguson. 2013. Florida Peach and Nectarine Varieties. .
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Morgan, K. and M. Olmstead. 2013. A Diversification Strategy for Perennial Horticulture in Florida. HortTechology. 23(4):482-489.
• Type: Journal Articles Status: Published Year Published: 2012 Citation: Olmstead, M.A., T.W. Miller, C.S. Bolton (g), and C.A. Miles. 2012. Weed Control in a Newly Established Organic Vineyard. HortTechnology. 22:757-765.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2013 Citation: Morgan, K. and M. Olmstead. 2013. Peach orchard establishment and production planning budgets for Florida. Proceedings of the Florida State Horticultural Society.
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Olmstead, M. 2013. Low-chill peach production in Florida. 2012 Proceedings of the Florida State Horticultural Society. Cover photo and description.
• Type: Other Status: Published Year Published: 2013 Citation: Olmstead, M.A., J. Chaparro, J.G. Williamson, R. Rouse, R. Mizell, P. Harmon, and J. Ferguson. 2013. Florida Subtropical Peaches and Nectarines: Production Practices. .
• Type: Other Status: Published Year Published: 2013 Citation: Olmstead, M.A., and K. Morgan. 2013. Orchard Establishment and Production Budget for Stone Fruit Production in Florida. .

Progress 10/01/11 to 09/30/12

Outputs
OUTPUTS: Rootstock Evaluation: Four rootstocks with commercial potential, and budded with UFSun were planted at the Plant Science Research and Education Unit in Citra, FL. Initial trunk-cross sectional area measurements were made, with the majority of growth measurements commencing in 2013. Nematode Resistance in Subtropical Peach Rootstocks: Preliminary field evaluation of Flordaguard x Prunus kansuensis and Okinawa x P. kansuensis F1 hybrids indicates that the former hybrids are resistant to M. floridensis, while the Okinawa x P. kansuensis hybrids is susceptible. These preliminary results indicate that P. kansuensis may carry a resistance gene(s) allelic to that found in Flordaguard. Funding was secured for this project, and a Ph.D. student was hired in January 2012. Efforts to maintain foundation populations of M. floridensis have been successful, and populations continue to build for the genetic study of resistance/tolerance in Flordaguard. Nematodes to build field populations were applied in preparation of the fumigation studies to evaluate reduced rates of Telone (1,3-Dichloropropene). These rates will be applied in the before susceptible and resistant rootstocks are planted in plots. Optimal Nitrogen Rates: Four nitrogen treatments and a control (no nitrogen added) were applied to mature 'TropicBeauty' trees beginning in spring of 2011, and have continued into 2012. These treatments include: N0 = 0 kg/ha (0 lb N/acre) N1 = 45 kg N/ha (40 lb N/acre) N2 = 90 kg N/ha (80 lb N/acre) N3 = 179 kg N/ha (160 lb N/acre) N4 = 269 kg N/ha (240 lb N/acre) Trunk caliper measurements, vegetative and floral bud measurements were recorded, and soil samples at two depths were taken throughout the plot. Single tree replicates were set up in a completely randomized design (N=6). A severe freeze in February 2012 reduced crop on all trees throughout the orchard to 20% of a full crop. Remaining fruit were harvested and analyzed for a second year and included Brix, pH, and titratable acidity. Fruit size and total yield was recorded for each replicate. Summer pruning weights and total leaf nitrogen was measured and analyzed for each treatment. This experiment will be replicated in 2013. A similar setup was being initiated in a newly planted orchard; however, there is an additional factor for evaluation, which includes application method (granular [banded] vs. fertigation). The same nitrogen treatments were applied throughout the growing season either monthly (granular applications) or weekly (fertigation applications). Leaching potential will be analyzed with soil sampling at key phenological stages throughout the growing season, as suction cup lysimeters were not consistent in sampling soil water leachate in sandy soil. Research program findings were disseminated to scientists through participation in scientific meetings and scientific publications. PARTICIPANTS: Mercy Olmstead (Principle Investigator) Matthew Ross (Biological Scientist) TRAINING and PROFESSIONAL DEVELOPMENT: Daniel Mancero-Castillo (Doctor of Plant Medicine Student) TARGET AUDIENCES: The primary target audiences for this project are stone fruit producers in the Southern/Southeastern United States, and research and extension scientists working in stone fruit production. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The unique growing conditions in Florida allow producers to sell peaches when there is little else on the market, after imports from South America have slowed. This allows growers to command a premium price with increasing demand from consumers for this tree-ripe Florida fruit. However, these unique growing conditions in a subtropical environment demand that production practices are altered to produce premium quality fruit. Identifying the ideal nitrogen rate will allow growers to produce high quality fruit while minimizing environmental impacts from leaching and optimize tree health and longevity. Optimizing tree health is maximized in Florida by growing scions on rootstocks that are resistant to Meloidogyne floridensis, the peach root-knot nematode currently only found within the state of Florida. A sole commercially-acceptable resistant rootstock, Flordaguard is particularly susceptible to fungal gummosis. Thus, identifying genes associated with peach root-knot nematode resistance in Flordaguard will allow us to construct markers associated with this trait. These marker(s) can then be used in marker-assisted breeding efforts, which will greatly decrease the time to breed additional rootstocks containing resistance to M. floridensis.

Publications

• Olmstead, M. and S. Futch. 2012. Using an Ethylene Inhibitor to Increase Fruit Size, Firmness, and Storage Quality in Florida Peach Production. Proceedings of the Florida State Horticultural Society. Vol. 125: xx-xx. (Accepted, in press).
• Wegrzyn J.L., D. Main, B. Figueroa, M. Choi, J. Yu, D.B. Neale, S. Jung, M. Stanton, P. Zheng, S. Ficklin, I. Cho, C. Peace, K. Evans, G. Volk, N. Oraguzie, C. Chen, F.G. Gmitter, Jr., M. Olmstead, and A.G. Abbott. 2012. Uniform Standards for Genome Databases in Forest and Fruit Trees. Tree Genetics and Genomes. 8(3):549-557
• Olmstead, M.A., T.W. Miller, C.S. Bolton, and C.A. Miles. 2012. Weed Control in a Newly Established Organic Vineyard. HortTechnology. Accepted, in press.
• Morgan, K.L. and M.A. Olmstead. 2012. Building a Foundation for the Florida Stone Fruit Industry: Results from a Grower Survey. HortTechnology. In review.
• Andersen, P.C., J.G. Williamson, and M.A. Olmstead. 2012. Sustainability Assessment of Fruit and Nut Crops in North Florida and North Central Florida. .
• Olmstead, M.A., J. Chaparro, and J. Ferguson. 2012. Rootstocks for Florida Stone Fruit. . In press.

Progress 10/01/10 to 09/30/11

Outputs
OUTPUTS: Rootstock Evaluation Four rootstocks with commercial potential were budded with a scion, UFSun to prepare for spring 2012 plantings in an experimental plot to be located at the Plant Science Research and Education Unit in Citra, FL. Potted trees were kept in a screenhouse while awaiting planting during the spring 2012 season. Nematode Resistance in Subtropical Peach Rootstocks Preliminary field evaluation of Flordaguard x Prunus kansuensis and Okinawa x P. kansuensis F1 hybrids indicates that the former hybrids are resistant to M. floridensis, while the Okinawa x P. kansuensis hybrids is susceptible. These preliminary results indicate that P. kansuensis may carry a resistance gene(s) allelic to that found in Flordaguard. Funding was secured for this project, and a Ph.D. student was hired in January 2012. Efforts to maintain foundation populations of M. floridensis have been successful, and populations continue to build for both the genetic study of resistance/tolerance in Flordaguard and fumigation studies to evaluate reduced rates of Telone (1,3-Dichloropropene). Optimal Nitrogen Rates Four nitrogen treatments and a control (no nitrogen added) were applied to mature TropicBeauty trees beginning in spring of 2011. These treatments include no additional nitrogen added (0), 40 lbs/acre N, 80 lbs N/acre, 120 lbs N/acre, and 240 lbs N/acre. Initial trunk caliper measurements, vegetative and floral bud measurements were recorded, and initial soil samples were taken throughout the plot. Single tree replicates were set up in a completely randomized design (N=6). Fruit were harvested and analyzed for Brix, pH, and TA. Fruit size and total yield was recorded for each replicate. Summer pruning weights and total leaf nitrogen was measured and analyzed for each treatment. This experiment will be replicated in 2012 and 2013. A similar setup is being initiated in a newly planted orchard; however an additional factor will be the evaluation of granular (banded) vs. fertigation. The same nitrogen treatments will be applied throughout the growing season either monthly (granular applications) or weekly (fertigation applications). Soil water samples will be collected within and below the rootzone to monitor potential leaching from these treatments. Similar measurements as in the mature tree study will be taken and analyzed. Research program findings were disseminated to scientists through participation in scientific meetings and scientific publications. PARTICIPANTS: PROJECT: Mercy Olmstead (Principal Investigator), Wade Davidson (Biological Scientist) COLLABORATORS: Jose Chaparro (Univ. of FL, Stone Fruit Breeder), Thomas Beckman (USDA-ARS, Byron, GA), Jeff Williamson (Univ. of FL, Extension Specialist), Kim Morgan (Miss. St. Univ., Agricultural Economist), Andrew Nyczepir (USDA-ARS, Byron, GA), Lincoln Zotarelli (Univ. of FL, Extension Specialist), Jeffrey Brecht (Univ. of FL, Postharvest Biologist), Thomas Obreza (Univ. of FL, Interim Assistant Extension Dean) TRAINING AND PROFESSIONAL DEVELOPMENT: Diana Edlin (Ph.D Student) TARGET AUDIENCES: TARGET AUDIENCES: The primary target audiences for this project are stone fruit producers in the Southern/Southeastern United States, and research and extension scientists working in stone fruit production. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The unique growing conditions in Florida allow producers to sell peaches when there is little else on the market, after imports from South America have slowed. This allows growers to command a premium price with increasing demand from consumers for this tree-ripe Florida fruit. However, these unique growing conditions in a subtropical environment demand that production practices are altered to produce premium quality fruit. Identifying the ideal nitrogen rate will allow growers to produce high quality fruit while minimizing environmental impacts from leaching and optimize tree health and longevity. Optimizing tree health is maximized in Florida by growing scions on rootstocks that are resistant to Meloidogyne floridensis, the peach root-knot nematode currently only found within the state of Florida. A sole commercially-acceptable resistant rootstock, Flordaguard is particularly susceptible to fungal gummosis. Thus, identifying genes associated with peach root-knot nematode resistance in Flordaguard will allow us to construct markers associated with this trait. These marker(s) can then be used in marker-assisted breeding efforts, which will greatly decrease the time to breed additional rootstocks containing resistance to M. floridensis.

Publications

• Wegrzyn J.L., D. Main, B. Figueroa, M. Choi, J. Yu, D.B. Neale, S. Jung, M. Stanton, P. Zheng, S. Ficklin, I. Cho, C. Peace, K. Evans, G. Volk, N. Oraguzie, C. Chen, F.G. Gmitter, Jr., M. Olmstead, M, and A.G. Abbott. Uniform Standards for Genome Databases in Forest and Fruit Trees. (2011) Tree Genetics and Genomes. (accepted, in press).
• Olmstead, M. and M. Keller. 2010. Reducing Grape Inflorescence Length to Decrease Cluster Compactness. HortScience 45(8): S314.
• Main, D., S. Jung, C. Peace, K. Evans, O, Nnadozie, F. Gmitter, C. Chen, L. Mueller, D. Layne, M. Olmstead, M. Staton, A. Abbott. 2010. Tree Fruit GDR: Translating Genomics Into Advances in Horticulture. HortScience 45(8):S204.
• Olmstead, M.A., J. Chaparro, and P. Conner. 2011. Propagating Fruit Plants in Florida. Revision of SP-171. IFAS Communications.
• Olmstead, M.A. J. Williamson, J. Chaparro, and T. Crocker. 2011. Alternative Opportunities for Small Farms: Peach and Nectarine Production Review. .
• Olmstead, M., G. England and R. Atwood. 2011. Optimizing Fruit Spacing in Florida Peach Production. Proceedings of the Florida State Horticultural Society. Vol. 124::xx-xx.
• Olmstead, M.A. 2011. Florida growers diversify with peaches. Good Fruit Grower, July 2011. Olmstead, M. and R. Rouse. 2011. Growing Florida stone fruit as an alternative to citrus production. Citrus Industry, 92:14-17.